Systematic analysis of the interplay between synthesis route, microstructure, and thermoelectric performance in p-type Mg2Si0.2Sn0.8

Synergistic modulation of the thermoelectric performance of melt-spun p-type Mg2Sn via Na2S and Si alloying

“…Notably, the (Mg 2 Sn 0.9 Si 0.1 ) 0.93 (Na 2 S) 0.07 sample achieves a high near-room-temperature power factor close to 1.3 mW m À1 K À2 and an excellent peak power factor of 1.8 mW m À1 K À2 (at 673 K) that increases by 73% compared to the power factor obtained in the (Mg 2 Sn) 0.93 (Na 2 S) 0.07 sample at the same temperature. Although this value is still lower than the reported peak power factor of Ag-doped Mg 2 Sn, 34 it has already exceeded many other p-type polycrystalline Mg 2 (Sn,Si) alloys, including Ag-doped, 28,37,54 Li-doped, 26,27,52,53,57 Na-doped 18,36,38,39 and Gadoped 34,58 Mg 2 (Sn,Si).…”

“…3f) is obtained at 623 K for (Mg 2 Sn) 0.93 (Na 2 S) 0.07 , which is much higher than that of the pristine Mg 2 Sn ($0.01). Nevertheless, such a peak zT value is still relatively low when compared with zT values reported for Mg 2 (Si,Sn) with Li doping 26,27,52,53 or Ag doping, 28,54 but shows more potential than p-type Mg 2 (Si,Sn) doped with CH 3 COONa 38 or Na 2 CO 3 (ref. 39).…”

“…(e) Diagram of S 2 s and 1/k L of various Mg 2 (Sn,Si) materials. (f)Comparison between the peak zT of our (Mg 2 Sn 0.9 Si 0.1 ) 0.93 (Na 2 S) 0.07 and previously reported data 18,26,29,34,39,53,57,58,63,64.…”

“…Comparison between the peak zT of our (Mg 2 Sn 0.9 Si 0.1 ) 0.93 (Na 2 S) 0.07 and previously reported data. 18,26,29,34,39,53,57,58,63,64…”

“…25 However, p-type Mg 2 (Si,Sn) does not perform as well as its n-type counterpart. For example, the most typical p-type samples are Li/Ag-doped Mg 2 (Si,Sn): a zT of 0.4 was obtained at 700 K in Li-doped Mg 2 Si 0.2 Sn 0.8 fabricated by high-energy ball milling and induction melting; 26 Li doping effectively reduced the density of states effective mass of Mg 2 -Si 0.3 Sn 0.7 synthesized by a two-step solid-state reaction method, which resulted in a peak zT of 0.5 at 723 K; 27 Tang et al synthesized p-type Ag-doped Mg 2 Si 0.4 Sn 0.6 via melt spinning, which effectively suppressed the thermal conductivity and led to a maximum zT of 0.45 at 690 K. 28 Further enhancement in the thermoelectric performance of p-type Mg 2 (Si,Sn) is thus much desired, since both p-type and n-type materials are demanded for building thermoelectric legs for practical applications.…”